Scalable and fast three dimensional printing system

ABSTRACT

A three dimensional printing system includes a light engine having a spatial light modulator for curing individual layers of a photocure resin to form a three dimensional article of manufacture. The light engine is configured to: (1) receive a slice image that defines an array of energy values for curing a layer, (2) process the slice image to define an image frame compatible with the spatial light modulator, (3) receive an on signal, (4) activate the first light source in response to the on signal; (5) repeatedly send the first defined image frame to the first spatial light modulator during a defined cure time for the single layer of resin; (6) receive an off signal; (7) deactivate the first light source in response to the off signal; and (8) repeat steps (1) - (7) until the three dimensional article of manufacture is formed.

FIELD OF THE INVENTION

The present disclosure concerns an apparatus and method for the digitalfabrication of three dimensional articles of manufacture through thesolidification of liquid photon-curable (photocure) resins. Moreparticularly, the present disclosure concerns an advantageous method ofcontrolling a light engine that is scalable from one to multiple lightengines in a three dimensional printing system.

BACKGROUND

Three dimensional printers are in widespread use. Examples of threedimensional printer technologies includes stereolithography, selectivelaser sintering, and fused deposition modeling to name a few.Stereolithography-based printers utilize a controllable light engine toselectively harden or solidify a liquid photocure resin one layer at atime. In some embodiments the light engine includes a light source thatilluminates a spatial light modulator.

Some of these light engines originate from projectors that are used fordisplaying images and video. When these light engines are used for threedimensional printers, certain inefficiencies result because these lightengines have electronics optimized for the display of full motion video.There is a need to redesign the electronics to be optimal for threedimensional printing.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic block diagram of a three dimensional printingsystem.

FIG. 2 is a diagram representing a build plane for a single lightengine.

FIG. 3 is an electrical block diagram of an exemplary light engine.

FIG. 4 is a timing diagram of an exemplary sequence of bit planes forone image frame.

FIG. 5 is a flowchart of an exemplary method for operating a threedimensional printing system.

FIG. 6 is a timing diagram to illustrate an exemplary operationalsequence for a three dimensional printing system.

FIG. 7 is a schematic block diagram of a three dimensional printingsystem having two or more light engines.

FIG. 8 is a diagram representing a composite build plane that is acomposite of four partially overlapping build fields of four lightengines.

FIG. 9 is an electrical block diagram depicting four exemplary lightengines.

FIG. 10 is a flowchart of an exemplary method for operating a threedimensional printing system having more than one light engine.

SUMMARY

In a first aspect of the invention, a three dimensional printing systemincludes a vessel for containing photocure resin, a fixture forsupporting a three dimensional article of manufacture, a movementmechanism for incrementally displacing the fixture, a light engine, anda controller that is electrically or wirelessly coupled to the movementmechanism and the light engine. The vessel includes a lower surfacehaving a transparent sheet in contact with the photocure resin. Thethree dimensional article of manufacture has a lower face that is infacing relation with the transparent sheet. The light engine isconfigured to apply pixelated light through the sheet and to the lowerface in order to solidify thin slices of the photocure resin proximateto a build plane. The build plane defines a lateral area that the lightengine is capable of curing. The controller activates the light engineto perform the following steps: (a) receive a first incoming sliceenergy data array; (b) process the first incoming slice energy dataarray to define a first image frame; (c) receive an on signal; (d)activate the first light source in response to the on signal; (e)repeatedly send the first defined image frame to the first spatial lightmodulator during a defined cure time for a layer of the resin; (f)receive an off signal; (g) deactivate the first light source in responseto the off signal; and (h) repeat steps (a) - (g) until the threedimensional article of manufacture is formed.

In one implementation the light engine includes a system processorcoupled to a digital mirror device module and a light source module. Inone embodiment the digital mirror device module includes an imagescaler, a digital mirror device formatter, and a digital mirror device.The image scaler processes the received first slice image to do one ormore of correction, calibration, scaling, and stitching and to provide ascaled energy data array. The digital mirror device formatter convertsthe scaled energy data array into an image frame compatible with thedigital mirror device. The digital mirror device includes a digitalmirror array which includes at least one million individuallyaddressable mirror elements. The light source module includes a lightsource driver coupled to a light source.

In another implementation the first image frame defines a sequence ofbit planes for individual pixel elements of the first spatial lightmodulator. An energy value delivered for each pixel element isdetermined by which bit planes are in an “on” state. Thus, the firstimage frame is an array of binary numbers with bit positions in a binarynumber corresponding with a bit plane.

In yet another implementation the first light source is activatedsimultaneously with a “temporal leading edge” of one of the definedimage frames. The temporal leading edge of an image frame is the lefthand side of an image frame in a time domain - it is when the imageframe begins to affect operation of the spatial light modulator. Thusthe first light source is turned on simultaneously with the activationof the first spatial light modulator with one of the defined imageframes.

In a further implementation an integer number of the defined imageframes are received by the first spatial light modulator between theactivation and the deactivation of the light source.

In a yet further implementation a non-integer number of the definedimage frames are received by the spatial light modulator between theactivation and the deactivation of the light source.

In another implementation the three dimensional printing system includesa second light engine including a second light source that illuminates asecond spatial light modulator, the second light engine configured to:(a) receive a second incoming slice energy data array, the secondincoming slice energy data array is complementary with the firstincoming slice energy data array to allow the first and second lightengines to have different but partially overlapping build fields; (b)process the incoming slice energy data array to define a second imageframe; (c) receive the on signal from the first light engine; (d)activate the second light source in response to the on signal; (e)repeatedly send the second defined image frame to the second spatiallight modulator during the defined cure time; (f) receive the off signalfrom the first light engine; (g) deactivate the second light source inresponse to the off signal; and (h) repeat steps (a) - (g) until thethree dimensional article of manufacture is formed.

In yet another implementation the first light engine sends the incomingslice energy data array along a first data path to a digital mirrordevice module and sends the on and off signals along a second data pathto a first light source module.

In a second aspect of the invention, a three dimensional printing systemincludes a vessel for containing photocure resin, a fixture forsupporting a three dimensional article of manufacture, a movementmechanism for incrementally displacing the fixture, a light engine, anda controller that is electrically or wirelessly coupled to the movementmechanism and the light engine. The vessel includes a lower surfacehaving a transparent sheet in contact with the photocure resin. Thethree dimensional article of manufacture has a lower face that is infacing relation with the transparent sheet. The light engine isconfigured to apply pixelated light through the sheet and to the lowerface in order to solidify thin slices of the photocure resin proximateto a build plane. The build plane defines an area that the light engineis capable of curing. The light engine includes a light source, aspatial light modulator that is illuminated by the light source, asystem processor for receiving an incoming slice energy data array andlight source switching signals; an image scaler that receives andprocesses the incoming slice energy data array and outputs a scaledenergy data array after one or more of correcting, calibrating, scaling,and stitching of the incoming slice energy data array; a digital mirrordevice formatter that receives and converts the scaled energy data intoan image frame and repeatedly sends the image frame to the spatial lightmodulator; and a light source driver that receives the light sourceswitching signals and turns the light source on for a cure time durationthat overlaps with the repeated image frame. In a first embodimentturning the light source on is synchronized with the start of one of theimage frames. In a second embodiment an integer number of the imageframes are received by the spatial light modulator while the lightsource is on. In a third embodiment a non-integer number of the imageframes are received by the spatial light modulator while the lightsource is on.

In one implementation the light engine is a plurality of light enginesconfigured to cooperatively generate a composite build plane, theplurality of light engines receiving different but complementaryincoming slice energy data arrays. The plurality of light enginesincludes a master light engine and at least one subsidiary light engine,the master light engine receives the switching signals and routes themto the at least one subsidiary light engine.

In a third aspect of the invention a three dimensional printing systemincludes a vessel for containing photocure resin, a fixture forsupporting a three dimensional article of manufacture, a movementmechanism for incrementally displacing the fixture, a plurality of lightengines, and a controller that is electrically or wirelessly coupled tothe movement mechanism and the plurality of light engines. The vesselincludes a lower surface having a transparent sheet in contact with thephotocure resin. The three dimensional article of manufacture has alower face that is in facing relation with the transparent sheet. Thelight engines are configured to apply pixelated light through the sheetand to the lower face in order to solidify thin slices of the photocureresin proximate to a composite build plane. The composite build planedefines an area that the light engine is capable of curing. Theplurality of light engines include a master light engine and at leastone subsidiary light engine. The master light engine includes a systemprocessor that is configured to: (a) receive an incoming slice energydata array specific to the master light engine; (b) receive light sourceswitching signals; (c) route the incoming slice energy data arrayspecific to the master light engine to a digital mirror device modulethat is within the master light engine; (d) apply the switching signalsto a light source module that is within the master light engine; and (e)route the switching signals to the at least one subsidiary light engine.

In one implementation the composite build plane is defined by aplurality of partially overlapping build fields. Each build field isindividually formed by one of the plurality of light engines.

In another implementation the digital mirror device module includes animage scaler, a digital mirror device formatter, and a digital mirrordevice. The image scaler processes the incoming slice energy data arrayto define a scaled energy data array and the digital mirror deviceformatter processes the scaled energy data array to define an imageframe. The switching signals include an on signal and an off signal. Acure time is defined by a time duration between the on signal and theoff signal. The digital mirror device formatter is configured tosequentially send an integer number of image frames to the digitalmirror device during the cure time.

In yet another implementation the digital mirror device module includesan image scaler, a digital mirror device formatter, and a digital mirrordevice. The image scaler processes the incoming slice energy data arrayto define a scaled energy data array and the digital mirror deviceformatter processes the scaled energy data array to define an imageframe. The switching signals include an on signal and an off signal. Acure time is defined by a time duration between the on signal and theoff signal. The digital mirror device formatter is configured tosequentially send a non-integer number of image frames to the digitalmirror device during the cure time.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a schematic block diagram of an exemplary three dimensionalprinting system 2. In describing this the following figures, mutuallyperpendicular axes X, Y and Z will be used. Axes X and Y are lateralaxes. In some embodiments X and Y are also horizontal axes. Axis Z is acentral axis. In some embodiments Z is a vertical axis. In someembodiments the direction +Z is generally upward and the direction -Z isgenerally downward.

Three dimensional printing system 2 includes a vessel 4 containingphotocurable resin 6. Vessel 4 includes a transparent sheet 8 thatdefines at least a portion of a lower surface 9 of vessel 4. A lightengine 10 is disposed to project light up through the transparent sheet8 to solidify the photocure resin 6 and to thereby form the threedimensional article of manufacture 12. The three dimensional article ofmanufacture 12 is attached to a fixture 14. A movement mechanism 16 iscoupled to fixture 14 for translating the fixture 14 along the verticalaxis Z.

A controller 18 is electrically or wirelessly coupled to the lightengine 10 and the movement mechanism 16. Controller 18 includes aprocessor (not shown) coupled to an information storage device (notshown). The information storage device includes a non-transient ornon-volatile storage device (not shown) that stores instructions that,when executed by the controller 18 can be contained in a single IC(integrated circuit) or multiple ICs. Controller 18 can be at onelocation or distributed among multiple locations in three dimensionalprinting system 2. Processor controls the light engine 10 and themovement mechanism 16.

The three dimensional article of manufacture 12 has a lower face 20 thatfaces the transparent sheet 8. Between the lower face 20 and thetransparent sheet 8 is a thin layer of resin 22. As light engine 10applies light energy through the transparent sheet 8 it polymerizesresin proximate to a “build plane” 24 which can be coincident orproximate to the lower face 20.

The light engine 10 includes a light source 26, a spatial lightmodulator 28, and other devices (see FIG. 3 ). Light source 26illuminates spatial light modulator 28 which generates a pixelated imagethat is projected up through the transparent film 8. In an exemplaryembodiment, light source 26 includes one or more light emitting diodesand/or lasers. The light source 26 can generate blue or ultravioletlight for curing layers of resin 6. In an exemplary embodiment, thespatial light modulator 28 is a digital mirror device 28 that caninclude one million or more controllable mirror elements. Each mirrorelement (not shown) has at least two positions including an “on”position and an “off” position. In the “on” position it transmits lightto illuminate a “pixel element” 25 of the build plane 24. In an “off”position it leaves that pixel 25 element dark. (FIG. 2 illustrates thebuild plane 24).

Controller 18 controls the light engine 10 to selectively harden a newlayer of resin onto the lower face 20. After each layer of resin ishardened, controller 18 controls movement mechanism 16 to raise thethree dimensional article of manufacture 12 to allow for replenishmentof the thin layer of resin 22.

FIG. 2 depicts the lateral build plane 24 for a fixed value of Z. Thelateral build plane 24 is defined a lateral extent of the light enginein X and Y for the fixed value of Z. The lateral build plane 24 has acenter 30 and lateral edges 32. Lateral edges 32 define the lateralextent of the lateral build plane 24. While the lateral build plane 24is shown as rectangular it is to be understood that distortions andother artifacts may render the lateral build plane 24 to have nonlinearlateral edges 32 and/or a non-rectangular shape.

Within the lateral build plane 24 are pixel elements 25. Each pixelelement 25 is defined by the spatial light modulator 28. In an exemplaryembodiment, each pixel element 25 corresponds to a mirror element of thespatial light modulator 28. FIG. 2 depicts build plane 20 as having farfewer pixel elements 25 than a real system for illustrative simplicity.In practice, build plane 20 can have one million or more individualpixel elements 25.

FIG. 3 is an electrical block diagram depicting light engine 10 whichincludes system processor 34 that is coupled to information storagedevice 36, light source module 35, and digital mirror device module 37.Light source module 35 includes light source driver 42 and light source26. Digital mirror device module 37 includes image scaler 38, digitalmirror device formatter 40, and digital mirror device 28.

System processor 34 orchestrates most or all of the major functions ofthe light engine 10. System processor 34 is configured to receive anincoming slice energy data array from controller 18 that defines atleast a portion of a new layer of the article of manufacture 12. Theincoming slice energy data array defines a two dimensional array ofenergy values that define optical cure energy to be applied versusposition in X and Y. The spacing of the energy values in X and Y may ormay not correspond to the pixel array on the spatial light modulator 28.The system processor 34 transmits the incoming slice energy data arrayto the image scaler 38 of the digital mirror device module 37.

Information storage device 36 can include one or more memory devicesthat store incoming or processed data for the system processor 34. Suchdata can include the incoming slice energy data array.

Image scaler 38 processes the incoming image slice data to provide oneor more of correction, calibration, scaling, and stitching. Correctionincludes de-warping, and corrections for distortions such as barreldistortion and the keystone effect. Calibration can include compensationfor light source 26 output and variation in an optical path length fromthe light engine 10 to the build plane 24. Scaling can include remappingand frame rescaling. Remapping is the conversion of the incoming dataarray spacing of energy values to the spacing of the pixel array of thespatial light modulator 28. Frame rescaling is the scaling of the energyvalues from a total energy per pixel element 25 to an energy value perpixel element for one frame. For example, if it takes 10 frames toprovide a required cure time with light source 26, then the energyvalues would be reduced by 90% for each frame. Finally, stitchingadjustments are performed when more than one light engine is used todefine a build plane 24. In some alternative embodiments, part of thecorrection, calibration, scaling, and stitching can be performed by thecontroller before the data is passed to the digital mirror device module37 or by the digital mirror device formatter 40. Then the image scaler38 may not need to perform all of these functions. After these functionsare performed, the image scaler 38 passes resultant scaled energy dataarray to the spatial light modulator formatter 40.

Digital mirror device formatter 40 formats the scaled energy data arrayto a format compatible with the digital mirror device 28. The scaledenergy data array has a scaled (for the frame period) energy value foreach pixel. The digital mirror device formatter 40 converts each scaledenergy value into a binary number corresponding to a sequence of bitplanes. A sequence of bit planes is depicted in FIG. 4 . Each bit planeis a time duration during which a pixel element is either on or off.When a binary value of 1 is sent for a given bit plane, the pixelelement is then turned on during the bit plane time duration. When abinary value of 0 is sent for a given bit plane, the pixel element isturned off for the bit plane time duration. FIG. 4 illustrates a 6 bitimage frame. The bit planes include a least significant bit (LSB) or bitzero that is the narrowest time duration defined for a mirror element tobe on or off. The next most significant bit (bit one) has twice the timeduration of bit zero. This repeats up to the most significant bit (MSB).While FIG. 4 depicts a six bit frame for simplicity, other systems mayutilize 8 bit frames or more or less bits. A binary number of 101010would have bit zero turned on, bit two turned off, but three turned on,and so on for a six bit frame. The binary number thus defines the framedata for a given pixel element. The digital mirror device formatter 40sends the image frame data for the build plane 24 to the digital mirrordevice 28 which sequentially activates and deactivates the individualmirror elements accordingly.

The system processor 34 is configured to receive switching signals fromcontroller 18 and to pass the switching signals to the light sourcedriver 42 of the light source module 35. For embodiments having morethan one light engine 10, the system processor 34 can also send theswitching signals to other light engines 10. The light source driver 42provides power to the light source 26. In an exemplary embodiment lightsource 26 is a light emitting diode (LED) that emits ultraviolet (UV)light. The switching signals include an “on” signal that activates(turns on) the light source 26 and an “off” signal that deactivates(turns off) the light source 26. In other embodiments the light source26 includes one or more of a laser and a blue light emitter.

Also depicted in FIG. 3 is the transmission of light (thicker grayarrows 44 and 46) through the three dimensional printing system 2.Element 44 depicts the “raw” or unprocessed light emitted by the lightsource 26. Element 46 depicts the pixelated light that is reflected bythe digital mirror device 28 and to optics that in turn deliver thepixelated light to the build plane 24.

FIG. 5 is a flowchart and FIG. 6 is a timing diagram depicting anexemplary method 48 of operation for the three dimensional printingsystem 2. According to step 50, the system processor 34 receivesincoming slice N energy data array (from controller 18) to solidify anN_(th) layer of the three dimensional article of manufacture 12. Systemprocessor 34 delivers the incoming slice N energy data array to theimage scaler 38. Step 50 is depicted as the top graph in FIG. 6 .Receipt of slice N and slice N+1 image data is represented as the uparrows.

According to step 52 the image scaler 38 processes the slice N imagedata to provide one or more of correction, calibration, scaling, andstitching. As an alternative, one or more of these functions can occurin controller 18 or in the digital mirror device formatter 40. Oneadvantage over performing such functions in controller 18 is speedbecause the components of the digital mirror device module 37 hasdedicated hardware that can perform these functions very rapidly. Theimage scaler 38 then delivers a scaled energy data array to digitalmirror device formatter 40.

According to step 54 the digital mirror device formatter 40 converts thescaled energy data array to an image frame having representation of bitplanes (as depicted in FIG. 4 for one image frame). According to step 56the formatted image frame data is repeatedly sent to the digital mirrordevice 28. The middle graph of FIG. 6 depicts six image frames beingsent to the digital mirror device 28 during a time duration thatcontains slice N. In general M frames are contained within a slice timeduration and can vary from one frame to any number that are sufficientto properly solidify a layer of resin 6.

In some embodiments each frame has a time duration of 1/30^(th) of asecond. A total cure time can be one or two seconds. A one second curetime would require 30 of such image frames. A two second cure time wouldrequire 60 image frames. In this exemplary embodiment one image framemay contain 8 bit planes. In other embodiments one image frame cancontain 12, 16, 24, or more bit planes depending upon a desired energyresolution.

Other cure times are possible depending on the cure speed of the resin 6being used. Other frame time durations are possible such as 1/50^(th) ofa second, 1/60^(th) of a second, and so on. The number of bit planesduring a frame can also vary depending upon the desired resolution.

Concurrent to the repeated sending of frames (step 56) steps 58 to 62are performed. According to step 58 the system processor 34 receives an“on” switching signal from controller 18. As part of step 58 systemprocessor 34 delivers the on signal to the light source driver 42 whichthen activates or turns on the light source 26.

According to step 60 the light source remains on during a cure time.During step 60 the digital mirror device formatter 40 continues to sendimage frames to the digital mirror device 28.

According to step 62 the system processor receives an “off” switchingsignal. As part of step 62 the system processor delivers the off signalto the light source driver 42 which then deactivates or turns off thelight source 26.

In some embodiments the on and off signals are sent by the systemprocessor to one or more subsidiary light engines 10. A subsidiary lightengine 10 would have an architecture similar to that of discussed withrespect to FIG. 3 . Such an arrangement will be discussed with respectto FIGS. 7-10 .

The lower timing diagram of FIG. 6 depicts steps 58-62. Arrows upindicate the light source 26 being turned on and the arrows downindicate the light source 26 being turned off. The horizontal axes ofFIG. 6 indicate exemplary relative timing of receiving slice data,delivery of frames, and activation and deactivation of the light source26. Various embodiments are possible.

In some embodiments activation of the light source 26 can besynchronized with the beginning of a frame. In other embodiments theyare not synchronized but the light source on and off occurs sometimeduring the delivery of the frames.

In some embodiments an integer number of frames are delivered by thedigital mirror device formatter 40 to the digital mirror device 28during the cure time of step 60. In other embodiments a non-integernumber of frames are delivered by the digital mirror device formatter 40to the digital mirror device 28 during the cure time of step 60.

According to step 64 controller 18 activates movement mechanism 16 toincrementally move the 3D article of manufacture 12 upward. According tostep 66 the value of N increments to N + 1 so that the N+1 slice imagedata can be received by the system processor 34. The sequence 48 repeatsuntil the 3D article of manufacture 12 is fully formed.

FIG. 7 is a schematic block diagram of an exemplary three dimensionalprinting system 2 which is similar to that depicted in FIG. 1 except forthe use of more than one light engine 10. This enables the imaging oflaterally larger 3D articles of manufacturing 12 without a reduction inresolution. Otherwise like element numbers indicate like or similarelements.

The light engines 10 (light engine A and light engine B) have a zone ofoverlap 68 over which both light engines 10 provide energy to the sameportion of the build plane 24. While two light engines 10 are shown, itis to be understood that the three dimensional printing system 2 caninclude one or more light engines 10 and can include any number of lightengines 10.

FIG. 8 depicts a composite build plane 24 that is formed by a compositeof four light engines A, B, C, and D. The different types of dashedoutlines indicate overlapping build fields within the composite buildplane 24 that are addressed by the light engines 10. For example, theupper left build field that is bounded by the dotted rectangle A is thefield of build plane 24 that is addressed by light engine A. Each of thebuild fields has a non-overlapping field portion and an overlappingfield portion. The overlapping field portion overlaps with one or moreof the other build fields. The indicated field portion 68 is an area ofbuild plane 24 over which build field A overlaps with build field fieldB. Indicated build field portion 70 is an area of build plane 24 overwhich all four build fields A, B, C, and D overlap. The composite buildplane 24 has an outer boundary 32 that is substantially rectangular butmay have a different shape due to various distortions such as a keystoneeffect and/or barrel distortion. Also, each of build fields A, B, C, andD may be likewise distorted in shape.

FIG. 9 is an electrical block diagram depicting four exemplary lightengines 10 according to capital letters A, B, C, and D. Refer to FIG. 3to see additional details applicable to these light engines 10. Thelight engines 10 includes a master light engine A and three subsidiarylight engines B, C, and D. The distinction between master and subsidiarylight engines 10 is related to the routing of signals and controllingand timing of a cure cycle. The master light engine A delivers theswitching signals to the subsidiary light engines B, C, and D whereby acure cycle for all four light engines 10 can be simultaneous.

A light engine 10 includes a system processor 34 coupled to a lightsource module 35 and a digital mirror device module 37 (see FIG. 3 formore details). The system processor 34 is configured to receive datafrom controller 18 for each new layer of photocure resin to beselectively cured onto the article of manufacture 12. Data transmittedfrom controller 18 to light engines 10 includes incoming slice energydata arrays and switching signals.

The incoming slice energy data arrays are indicated in FIG. 9 by “ADATA”, “B DATA”, “C DATA”, and “D DATA” for light engines A, B, C, and Drespectively. The four data arrays define a slice for the compositebuild plane 24 illustrated in FIG. 8 . As can be seen, the controller 18provides incoming slice energy data arrays directly to the individuallight engines 10. The data arrays are complementary and theyindividually include a non-overlapping array and an overlapping dataarray for a particular build field.

The switching signals are indicated by “SWITCH” in FIG. 9 . Theswitching signals are received by the system processor 34 of masterlight engine A which delivers the switching signals the light sourcemodule 35 within master light engine A. System processor 34 of masterlight engine A also delivers the switching signals to the subsidiarylight engines B, C, and D. The system processor within a subsidiarylight engine 10 then sends the switching signals to the light sourcemodule 35 which operates in the same way as the light source module 35of the master light engine 10. Having one master system processor 34 toreceive and deliver the switching signals to subsidiary systemprocessors 34 allows for synchronized and simultaneous operation of thelight engines 10 which increases the speed of a three dimensionalprinting system 2 having multiple light engines 10.

FIG. 10 is a flowchart depicting a method 78 of operation of a threedimensional printing system 2 having more than one light engine 10.According to step 80 the controller 18 sends a slice N energy data arrayto each of light engines A, B, C, and D. Slice N data refers to datathat defines an N_(th) layer of a three dimensional article ofmanufacture 12. The data received by a particular light engine 10 (A, B,C, or D) is different than the other light engines since it defines onebuild field which has a portion that overlaps the three other buildfields and a non-overlapping portion that is unique to that lightengine.

According to step 82 the individual light engines 10 separately processthe incoming slice N energy data arrays using image scaler 38. Step 82is similar to step 52 of FIG. 5 except that step 82 includes separateprocessing for the light engines 10. According to step 84 the data fromstep 82 is formatted for the individual spatial light modulators 28.According to step 86 image frames are repeatedly sent to lightmodulators 28. For a given light engine 10, this is the same as step 56of FIG. 5 and the middle graph of FIG. 6 .

According to step 88 the controller 18 sends an on pulse to the systemprocessor 34 of master light engine A. According to step 90 the systemprocessor 34 of master light engine A routes the on signal to the systemprocessors 34 for the subsidiary light engines B, C, and D. Also as partof step 90 the system processors 34 activate the light sources 26 forall of the light engines A, B, C, and D simultaneously. According tostep 92 the light sources 26 are on for a cure time for the layer N.According to step 94 the system processor 34 of master light engine Areceives an “off” signal. According to step 96 the system processor 34of light source A routes the off signal to the system processors 34 forthe subsidiary light sources B, C, and D. Also as part of step 96 thesystem processors 34 deactivate the light sources 26 for all of thelight engines A, B, C, and D simultaneously.

During the cure time 92 a plurality of the image frames are sent to thedigital mirror devices 28 for the individual light engines 10. Thetiming diagram depicted in FIG. 6 depicts a similar sequence if 50 isreplaced by step 80, step 56 is replaced by step 86, and steps 58-62 arereplaced with steps 88-96. As before the cure time 92 can contain aninteger or non-integer number of image frames. The start of the curetime can be synchronized or not synchronized to the start of an imageframe.

According to step 98 the movement mechanism 16 moves the threedimensionally article of manufacture 12 incrementally upward. Accordingto step 100 the N increments to N+1 for the next slice image data to bedelivered from controller 18 to the light engines 10. Steps 80 to 100can be repeated until the three dimensional article of manufacture 12 iscompleted.

The specific embodiments and applications thereof described above arefor illustrative purposes only and do not preclude modifications andvariations encompassed by the scope of the following claims. Forexample, while FIGS. 8-10 are described for four light engines 10, thetechnique of the disclosure can be applied to any number of lightengines 10.

1-20. (canceled)
 21. A three dimensional printing system including: avessel configured to contain photocure resin; a plurality of lightengines individually including a light source and a spatial lightmodulator; a control system including a controller, the control systemconfigured to operate portions of the three dimensional printing systemto form a three dimensional article from a sequence of selectivelyhardened layers of the photocure resin according to the followingcontrol system steps for an individual one of the sequence ofselectively hardened layers: receiving an incoming slice energy dataarray; processing the incoming slice energy data array to provide animage frame for individual ones of the plurality of light engines, theprocessing including: correcting the data array including one or more ofcorrecting distortions and de-warping; calibrating the data arrayincluding one or more of compensation for one or more of a light sourceand an optical path length; scaling the data array including for theimage frame; and stitching the data array to allow defining a compositebuild plane; for individual ones of the plurality of light engines,activating the light source; for individual ones of the plurality oflight engines, sending the image frame to the spatial light modulator;and for individual ones of the plurality of light engines, deactivatingthe light source.
 22. The three dimensional printing system of claim 21wherein the plurality of light engines define a corresponding pluralityof build fields that individually include a non-overlapping fieldportion and an overlapping field portion, the non-overlapping portion isunique to one light engine and the overlapping field portion is sharedby two or more light engines, the plurality of build fields form acomposite build field.
 23. The three dimensional printing system ofclaim 22 wherein the plurality of light engines include four lightengines, including an area of the composite build field over which thefour light engines overlap.
 24. The three dimensional printing system ofclaim 21 wherein the plurality of light engines are individually coupledto an image scaler that performs the processing the incoming sliceenergy data array to provide the image frame.
 25. The three dimensionalprinting system of claim 24 wherein a light engine of the plurality oflight engines includes a formatter that converts the image frame frompixel energy values from pixel energy values to a format compatible withthe spatial light modulator.
 26. The three dimensional printing systemof claim 21 wherein the controller performs the processing the incomingslice energy data array to provide the image frame before the imageframe is sent to individual ones of the plurality of light engines. 27.The three dimensional printing system of claim 26 wherein the lightengine includes a formatter that converts the image frame from pixelenergy values to a format compatible with the spatial light modulator.28. The three dimensional printing system of claim 21 wherein sendingthe image frame includes repeatedly sending a plurality of the sameimage frame to the spatial light modulator.
 29. The three dimensionalprinting system of claim 21 wherein the control system includes a mastersystem processor associated with a master light engine that deliverssignals to a subsidiary light engine.
 30. The three dimensional printingsystem of claim 21 wherein the control system includes a master systemprocessor associated with a master light engine that delivers signals toa plurality of subsidiary light engines.
 31. A three dimensionalprinting system including: a vessel configured to contain photocureresin; a plurality of light engines configured to selectively andsimultaneously illuminate a composite build plane and individuallycorresponding to one of a plurality of build fields that collectivelyform the composite build plane, the plurality of light enginesindividually including: a light source module including a light sourcedriver and a light source; and a digital mirror device module includinga digital mirror device; a control system including a controller, thecontrol system configured to operate portions of the three dimensionalprinting system to form a three dimensional article from a sequence ofselectively hardened layers of the photocure resin according to thefollowing control system steps for an individual one of the sequence ofselectively hardened layers: receiving an incoming slice energy dataarray; processing the incoming slice energy data array to provide animage frame for the individual light engines, processing the incomingslice energy data array including: correcting the data array includingone or more of correcting distortions and de-warping; calibrating thedata array including compensation for one or more of a light source andan optical path length; scaling the data array for the image frame; andstitching the data array to allow the formation of a composite buildframe from overlapping build fields; operating the light source driverto activate the light source to generate unprocessed light emitted fromthe light source that is directed to the digital mirror device; forindividual ones of the plurality of light engines, sending the imageframe to the digital mirror device, the digital mirror device respondsby processing the light received from the light source and reflectingprocessed light one of the overlapping build fields; and operating thelight source driver to deactivate the light source.
 32. The threedimensional printing system of claim 31 wherein the build fieldsindividually include a non-overlapping field portion that is unique toone of the plurality of light engines and an overlapping field portionthat is shared by at least two of the plurality of light engines. 33.The three dimensional printing system of claim 32 wherein the pluralityof light engines include four light engines, including an area of thecomposite build field over which the four light engines overlap.
 34. Thethree dimensional printing system of claim 31 wherein the plurality oflight engines individually include an image scaler that performs theprocessing the incoming slice energy data array to provide the imageframe.
 35. The three dimensional printing system of claim 34 wherein alight engine of the plurality of light engines includes a digital mirrordevice formatter that converts the image frame from pixel energy valuesto a sequence of bit planes.
 36. The three dimensional printing systemof claim 36 wherein the controller performs the processing the incomingslice energy data array to provide the image frame before the imageframe is sent to individual ones of the plurality of light engines. 37.The three dimensional printing system of claim 36 wherein the lightengine includes a digital mirror device formatter that converts theimage frame from pixel energy values to a sequence of bit planes. 38.The three dimensional printing system of claim 31 wherein sending theimage frame includes repeatedly sending a plurality of the same imageframe to the spatial light modulator.
 39. The three dimensional printingsystem of claim 31 wherein the control system includes a master systemprocessor associated with a master light engine that delivers signals toa subsidiary light engine.
 40. The three dimensional printing system ofclaim 31 wherein the control system includes a master system processorassociated with a master light engine that delivers signals to aplurality of subsidiary light engines.